You probably already know the perks of perennials. They come back year after year and are well-suited to almost any situation, whether a flower bed or a window box. But there's a subset of perennials that deserve an extra round of applause: those that have a long bloom period.

Long-Blooming Perennials That Thrive in the Sun

Our first three nominees are right at home in any sunny situation. They reward the eye when massed in sweeping drifts, blended in a border, or left to fend for themselves in a wild garden. Bonus: These long-flowering lovelies are also drought-tolerant.

Black-Eyed Susan (Rudbeckia 'Goldsturm' and other varieties)

These vibrant perennials offer showy yellow-orange petals with bronze-brown central cones. With a 3- to 4-inch span, black-eyed Susans are ideal for cutting—and you'll have plenty of time to snip a few for a vase. Blooming typically starts in midsummer and continues through autumn, especially if the plant is deadheaded.

Coreopsis 'Moonbeam'

This award-winning perennial flaunts a near-constant display of lemon-yellow daisy-shape flowers during the summer. You'll be rewarded with even longer bloom time if you shear the plant back by a few inches after heavy flushes of flowers. 'Moonbeam' and other varieties of coreopsis are great as cut flowers and can also be grown in large container gardens.

Penstemon 'Husker Red'

The "red" in Husker Red refers not to the flower but to the dramatic bronze-red foliage. (The "Husker" comes from the fact that the plant was developed at the University of Nebraska). This variety of penstemon grows up to 30 inches and sends up a score of airy flower stalks topped with hundreds of tubular white flowers. It's a favorite amongst butterflies and hummingbirds.

Long-Blooming Perennials That Thrive in the Shade

Coaxing flowers to survive in the shade is not really the bugaboo it's cracked up to be. While you can always rely on hostas and ferns to thrive under your trees, many other plants will also readily blossom and brighten shady spots. Here are three shade-loving perennials that go one step further, blooming for an extended period to provide color for up to three months.

Astilbe

With their feathery plumes, astilbes appear in a range of candy colors—red, pink, cream, white, salmon, even peach—and grow 1 to 3 feet tall, depending on the type. It's helpful to pay attention to which variety you purchase, since species influences the bloom time. What's the longest-blooming astilbe? Astilbe japonica typically blooms in late spring through early summer, while Astilbe chinensis cultivars flower from mid- to late summer. Select both types to enjoy astilbes practically all summer long.

Hellebore

These stunning perennials grow about 15 inches tall and bloom from late winter through early spring. After the petals fade, the sepals stay on the plant, making it look like it's still in bloom; that display can continue through midsummer. Hellebores feature shades of pink, red, purple, white, and green; some are double or have speckled petals. The plants are highly poisonous, but that means they're also deer- and rabbit-resistant.

Fernleaf Bleeding Heart (Dicentra)

These delicate-looking plants grow about a foot tall and wide. Most fernleaf bleeding hearts bloom on and off all spring, summer, and autumn in cool-summer climates. Look for varieties with pink, red, or white flowers.